The objective of this proposal is to conduce to molecular analysis of specific genes required for normal meiosis in Drosophila melanogaster, with the goal of analyzing the expression and elucidating the function of specific meiotic genes. Meiosis is a basic cellular process essential to the sexual reproduction of all higher organisms including man. The understanding of meiosis has relevance to important human health problems, because abnormal meiotic chromosome segregation leads to infertility and birth defects. Despite extensive cytological and genetic analysis, our understanding of meiosis is still rudimentary. The specific aims of this proposal include the isolation of the c(3)G and claret-nondisjunctional loci, two genes whose function is uniquely required for normal meiosis in Drosophila females. The c(3)G locus will be isolated by conducting a chromosomal walk through the region known to contain the locus, then mapped within the cloned region by correlating the cytogenetic and physical maps using a series of newly-induced deficiencies. The claret-nondisjunctional locus will be isolated by inducing insertion mutations, constructing genomic libraries from stocks containing these mutations, and screening those libraries with the mobile element known to be inserted in the claret locus. The localization of both genes within the cloned regions will be confirmed by transformation experiments. Both loci will also be subjected to further genetic analysis in parallel with their isolation; transcriptional expression of both loci will be analyzed following their isolation. The isolated genes will ultimately be (1) used as probes to analyze the stage and tissue specificity of gene expression, (2) incorporated into hybrid genes and introduced into Drosophila by transformation to search for regulatory elements, and (3) incorporated into fusion proteins to obtain antibodies to the gene products, which will in turn be used to determine the subcellular localization of the gene products. These methods provide a direct means of analyzing the expression and function of two genes required for normal meiosis in Drosophila, and of testing specific hypotheses (derived from previous genetic and cytological studies) regarding these two genes.